1. Field of the Invention
The present invention relates to a board stacking connector chip, which is interposed between two opposed printed boards, for stacking the printed boards.
2. Description of Related Art
Electronic equipment such as personal computers and telephone sets incorporates a large number of electronic components. For this reason, these electronic parts are generally contained in an equipment housing by being mounted dividedly on a plurality of printed boards. In order to achieve space saving and easy assembly, when a plurality of printed boards on which electronic components are mounted are contained in a housing, they are often contained in such a manner that the boards are arranged so as to be opposed to each other.
To arrange two printed boards so as to be opposed to each other, a system is possible in which connectors are interposed between the printed boards. Specifically, male connectors and female connectors are fixed at predetermined positions of the opposed surfaces of the respective two printed boards, and these connectors are fitted to each other, whereby the two printed boards are arranged oppositely. If each of the connectors is connected electrically to a conductor pattern on the printed board, the electrical conduction between the two printed boards can be achieved simultaneously.
As another system for oppositely arranging two printed boards, a system in which pins are interposed between the boards is also possible. With this system, the base of a pin is mounted on one of two opposed printed boards, and an insertion hole through which the tip end of the pin is inserted is formed on the other thereof. The pin is inserted through this insertion hole, and the tip end thereof and the periphery of insertion hole are joined by soldering. Thus, by interposing the pins between the boards as spacers, the two printed boards can be arranged oppositely. If the pin is a conductor, the electrical conduction between the conductor patterns of the two printed boards can be achieved simultaneously via the pin.
In recent years, the demand for high-density mounting of electronic components on a printed board has increased with the advance of the downsizing of electronic component and the improvement in component mounting technology. To meet this demand, as the electronic component mounting method, the surface mounting system has been used in place of the conventional insertion mounting system. The conventional insertion mounting system is a system in which the components are fixed by inserting the lead wires of electronic components through the holes in the printed board. In contrast, the surface mounting system is a system in which the electronic components such as chip components are directly mounted and soldered to the surfaces of conductor patterns on the printed board, such as FP (Flat Package) and SOP (Small Outline Package).
The surface mounting system, in which the aforesaid electronic components are soldered to the conductor patterns on the printed board while being brought into direct contact, has an advantage that the electronic component need not have a lead wire for mounting on the board. Moreover, the printed board need not be formed with a hole through which the lead wire passes, so that this system also has an advantage that a process of drilling holes in the board can be omitted. Further, since the electronic components can be mounted directly onto the conductor patterns on the printed board, the height of the electronic component from the board surface can be decreased, so that this system has an advantage that the clearance between the opposed printed boards can be reduced. Therefore, the space occupied by the printed boards can be saved.
However, in the conventional system in which two boards are arranged oppositely by interposing male connectors and female connectors between the printed boards, the clearance between the boards is determined by the heights of these connectors. Therefore, the clearance between the opposed printed boards cannot be decreased, so that the above-described advantage peculiar to the surface mounting method cannot be utilized.
Meanwhile, in the conventional system in which pins are interposed between the opposed printed boards, holes for inserting lead wires must be formed in one of the boards, so that an excess drilling process is required. For this reason, the advantage peculiar to the surface mounting method not requiring excess working on the printed board cannot be utilized. Also, stresses are concentrated at the solder joint portion of lead wire and conductor pattern by a deformation (for example, deflection of board) of printed board occurring with the passage of time, so that the solder joint portion is liable to be separated.